46 



June 21, 1848. 

 The President in the Chair. 



Present, fifteen members. 



Mr. Ayres gave an interesting account of some researches 

 he had been making in reference to an obscure point in the 

 anatomy of the genus Leuciscus. In the fish of this genus 

 the pharyngeal bones are armed with strong teeth, and by 

 the action of powerful muscles they are brought together, 

 crushing the food before it enters the stomach. For a long 

 time Mr, A. had failed to discover any point of origin for 

 the small muscles, whose function it is to separate these 

 bones after they have been brought in contact. He at last 

 discovered this to be a pair of extremely small, needle-like 

 bones, articulated perpendicularly upon the small bones 

 connecting the branchial arches. The tension upon these 

 delicate bones is sustained by two little ligaments extending 

 from their extremities, on the side opposite to the muscles, 

 to the roof of the mouth, like the backstays of a mast. Mr. 

 Ayres displayed this apparatus in L. pulchellus. He pre- 

 sented to the Society specimens of L. cornutus, L, atrina- 

 sus, and Fundulus fuscus. 



A portion of a letter from Dr. Mantell to the President of 

 the Society was read, in which he mentioned that he had 

 recently obtained exquisite specimens of the soft parts of 

 Foraminifera, preserved in chalk and flint. He had also 

 recently obtained a portion of the lower jaw of the adult 

 Iguanodon, with the teeth in place. Referring to the 

 sketch accompanying the letter, he says, 



" You will see, at a glance, that it is wholly unlike the jaw of 

 any reptile, and in truth is not similar to that of any creature, 

 recent or fossil. This relic is the right dentary bone (lower jaw) 

 with the symphysis perfect, two successional teeth in place, and 

 sockets for eighteen mature teeth, not one of which remains. 



